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Inconsistency in graph Example Code, Documentation
by Thomas F. O'Connell 20 Oct '03

20 Oct '03

This is a minor point but one worth correcting for the sake of correctness and ease of following the examples. In the boost-1.30.2 distribution, the file libs/graph/example/kevin-bacon.cpp makes a reference to a "./kevin-bacon.dat" file, but the file in both the distribution and the documentation is actually kevin_bacon.dat. The only difference being '_' vs. '-'. This is easily fixed by an end-user, but it would be nice to have the examples work out of the box. -tfo

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Bug in graph library transitive closure algorithm?
by Watson, Jean-paul 20 Oct '03

20 Oct '03

Is anyone aware of any bugs in the graph library 'transitive_closure' algorithm? I believe I have a concrete example that exhibits an obvious bug (in particular, missing vertices that are reachable from certain source vertices), but (1) wasn't sure if there was a work-around or some well-known avoidance tactic and (2) whether anyone was actively supporting the graph library components. Thanks! Jean-Paul Watson E-mail: jwatson(a)sandia.gov Discrete Math Dept (9215), MS 1110 Phone: (505) 845-8887 P.O. Box 5800, Sandia National Labs FAX: (505) 845-7442 Albuquerque, NM 87185-1110 USA (Old) URL: http://www.cs.colostate.edu/~watsonj <http://www.cs.colostate.edu/~watsonj>

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novice question: LAPACK & uBLAS
by Derek 18 Oct '03

18 Oct '03

Hi, I am a novice to all this. I am looking for a C++ library that would let me interface with BLAS/LAPACK. The immediate problem I have is the diagonalization of a large dense symmetric (possibly hermitian) matrix. (Speed will be a consideration eventually.) I would like to use the eigenproblem solvers in LAPACK. I understand that uBLAS does not have a full interface to LAPACK yet, but it looks like it is possible to use lapack at some level. (Does anyone have an example program excerpt?) I would be grateful for any advice about whether uBLAS is suitable for this. I am also considering other libraries such as MTL and Blitz++. I will be using Intel C++ compiler and/or GNU g++ on a Linux PC. Regards Derek

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Necessity of assert in iterators (as called from graph)?
by Thomas F. O'Connell 17 Oct '03

17 Oct '03

In trying to compile and run the Kevin Bacon example for graph in the 1.30.2 distribution of Boost, I was able to compile, but when I ran the executable, I got: kevin-bacon: /usr/local/boost-1.30.2/boost/token_iterator.hpp:75: void boost::detail::tokenizer_policy<Type, TokenizerFunc>::increment(Iterator&) [with Iterator = boost::iterator_adaptor<boost::detail::token_iterator_base<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >, boost::detail::tokenizer_policy<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::char_delimiters_separator<char, std::char_traits<char> > >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, const std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const std::basic_string<char, std::char_traits<char>, std::allocator<char> >*, std::forward_iterator_tag, ptrdiff_t>, Type = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, TokenizerFunc = boost::char_delimiters_separator<char, std::char_traits<char> >]: Assertion `b.base().valid_' failed. Aborted Investigating led me to comment out the asserts on lines 69 and 75 of boost/token_iterator.hpp just to test. When I rebuilt without the asserts, I was able to run my executable with no problem with seemingly correct output. What purpose do the asserts serve, and why would they be failing? -tfo

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RE: [Boost-users] [Q] shared_ptr c'tor
by Tom Matelich 17 Oct '03

17 Oct '03

The shared_ptr constructor from raw pointer is marked explicit (quick explanation: http://www.glenmccl.com/tip_023.htm) This is because once you put a pointer into a shared_pointer, it's lifetime is now managed by the shared_ptr. The authors feel it is very important that this is completely intentional, and rightly so. It can have nasty side effects if you don't. //untested code void foo(boost::shared_ptr<int> p) { (*p)++; } int main() { int* p = new int(5); foo(p); std::cerr << "p is now " << *p << std::endl; //oops, p has been deleted!!! return 0; } > -----Original Message----- > From: Marcel Loose [mailto:loose@astron.nl] > Sent: Friday, October 17, 2003 4:39 AM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] [Q] shared_ptr c'tor > > > Hi, > > I have a question related to the boost::shared_ptr constructor. > I want to be able to store boost::shared_ptr<Base> objects in > a std::vector. However, I don't want to bother my users with > the fact (implementation detail) that I'm using shared_ptrs > instead of raw pointers. > > The simplified sample code below more or less clarifies what > I want. The code in line 27 is the code I would like to be > able to use. Below that line, several attempts to get the > code to compile can be found. I understand that line 32 won't > compile, because it is equivalent to line 27. However, line > 37 left me puzzled. I would expect that the conversion of B* > to shared_ptr<B> would be trivial. Not so. > > Is it really true that the only way to use shared_ptr in the > way I want is as in lines 46, 47? Or am I overlooking > something? And is line 41 equivalent to line 46? > Thanks in advance. > > Regards, > > Marcel Loose. > > P.S.: I noticed that all code will compile if I omit the > "explicit" keyword in the constructor of shared_ptr, but I > don't consider that the proper way to solve the problem. > > > 1:#include <boost/shared_ptr.hpp> > 2:#include <vector> > 3: > 4:using namespace std; > 5:using namespace boost; > 6: > 7:class Base > 8:{ > 9:public: > 10: Base() { /* ... */ } > 11: virtual ~Base() {} > 12:}; > 13: > 14:class Derived : public Base > 15:{ > 16:public: > 17: Derived() { /* ... */ } > 18: virtual ~Derived() {} > 19:}; > 20: > 21: > 22:int main() > 23:{ > 24: vector<shared_ptr<Base> > v; > 25: > 26: { // failes to compile: > 27: v.push_back(new Derived()); // cannot > convert Derived*& > 28: } // to > shared_ptr<Base>. Why? > 29: > 30: { // failes to compile: > 31: Derived* d(new Derived()); // cannot > convert Derived*& > 32: v.push_back(d); // to > shared_ptr<Base>. Why? > 33: } > 34: > 35: { // failes to compile: > 36: Base* b(new Derived()); // cannot convert Base*& > 37: v.push_back(b); // to > shared_ptr<Base>. Huh? > 38: } // Seems a > trivial conversion. > 39: > 40: { // OK, this > compiles, but is > 41: shared_ptr<Derived> d(new Derived()); // it correct? > I.e. is conversion > 42: v.push_back(d); // > shared_ptr<Derived> to > 43: } // > shared_ptr<Base> trivial? > 44: > 45: { // OK, this > compiles, and is > 46: shared_ptr<Base> b(new Derived()); // probably > what I meant. > 47: v.push_back(b); // However, I > dislike the > 48: } // verbosity. > 49: > 50: return 0; > 51:} > > Just to be complete, please find the compiler diagnostics below. > > tBoost.cc: In function `int main()': > tBoost.cc:27: no matching function for call to ` > std::vector<boost::shared_ptr<Base>, > std::allocator<boost::shared_ptr<Base> > > >::push_back(Derived*&)' > /usr/local/gcc-3.2.1/include/c++/3.2.1/bits/stl_vector.h:490: > candidates are: > void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = > boost::shared_ptr<Base>, _Alloc = > std::allocator<boost::shared_ptr<Base> >] > tBoost.cc:32: no matching function for call to ` > std::vector<boost::shared_ptr<Base>, > std::allocator<boost::shared_ptr<Base> > > >::push_back(Derived*&)' > /usr/local/gcc-3.2.1/include/c++/3.2.1/bits/stl_vector.h:490: > candidates are: > void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = > boost::shared_ptr<Base>, _Alloc = > std::allocator<boost::shared_ptr<Base> >] > tBoost.cc:37: no matching function for call to ` > std::vector<boost::shared_ptr<Base>, > std::allocator<boost::shared_ptr<Base> > > >::push_back(Base*&)' > /usr/local/gcc-3.2.1/include/c++/3.2.1/bits/stl_vector.h:490: > candidates are: > void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = > boost::shared_ptr<Base>, _Alloc = > std::allocator<boost::shared_ptr<Base> >] > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users > ----------------------------------------------------------------------- DISCLAIMER: Information contained in this message and/or attachment(s) may contain confidential information of Zetec, Inc. If you have received this transmission in error, please notify the sender by return email. -----------------------------------------------------------------------

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[Q] shared_ptr c'tor
by Marcel Loose 17 Oct '03

17 Oct '03

Hi, I have a question related to the boost::shared_ptr constructor. I want to be able to store boost::shared_ptr<Base> objects in a std::vector. However, I don't want to bother my users with the fact (implementation detail) that I'm using shared_ptrs instead of raw pointers. The simplified sample code below more or less clarifies what I want. The code in line 27 is the code I would like to be able to use. Below that line, several attempts to get the code to compile can be found. I understand that line 32 won't compile, because it is equivalent to line 27. However, line 37 left me puzzled. I would expect that the conversion of B* to shared_ptr<B> would be trivial. Not so. Is it really true that the only way to use shared_ptr in the way I want is as in lines 46, 47? Or am I overlooking something? And is line 41 equivalent to line 46? Thanks in advance. Regards, Marcel Loose. P.S.: I noticed that all code will compile if I omit the "explicit" keyword in the constructor of shared_ptr, but I don't consider that the proper way to solve the problem. 1:#include <boost/shared_ptr.hpp> 2:#include <vector> 3: 4:using namespace std; 5:using namespace boost; 6: 7:class Base 8:{ 9:public: 10: Base() { /* ... */ } 11: virtual ~Base() {} 12:}; 13: 14:class Derived : public Base 15:{ 16:public: 17: Derived() { /* ... */ } 18: virtual ~Derived() {} 19:}; 20: 21: 22:int main() 23:{ 24: vector<shared_ptr<Base> > v; 25: 26: { // failes to compile: 27: v.push_back(new Derived()); // cannot convert Derived*& 28: } // to shared_ptr<Base>. Why? 29: 30: { // failes to compile: 31: Derived* d(new Derived()); // cannot convert Derived*& 32: v.push_back(d); // to shared_ptr<Base>. Why? 33: } 34: 35: { // failes to compile: 36: Base* b(new Derived()); // cannot convert Base*& 37: v.push_back(b); // to shared_ptr<Base>. Huh? 38: } // Seems a trivial conversion. 39: 40: { // OK, this compiles, but is 41: shared_ptr<Derived> d(new Derived()); // it correct? I.e. is conversion 42: v.push_back(d); // shared_ptr<Derived> to 43: } // shared_ptr<Base> trivial? 44: 45: { // OK, this compiles, and is 46: shared_ptr<Base> b(new Derived()); // probably what I meant. 47: v.push_back(b); // However, I dislike the 48: } // verbosity. 49: 50: return 0; 51:} Just to be complete, please find the compiler diagnostics below. tBoost.cc: In function `int main()': tBoost.cc:27: no matching function for call to ` std::vector<boost::shared_ptr<Base>, std::allocator<boost::shared_ptr<Base> > >::push_back(Derived*&)' /usr/local/gcc-3.2.1/include/c++/3.2.1/bits/stl_vector.h:490: candidates are: void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = boost::shared_ptr<Base>, _Alloc = std::allocator<boost::shared_ptr<Base> >] tBoost.cc:32: no matching function for call to ` std::vector<boost::shared_ptr<Base>, std::allocator<boost::shared_ptr<Base> > >::push_back(Derived*&)' /usr/local/gcc-3.2.1/include/c++/3.2.1/bits/stl_vector.h:490: candidates are: void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = boost::shared_ptr<Base>, _Alloc = std::allocator<boost::shared_ptr<Base> >] tBoost.cc:37: no matching function for call to ` std::vector<boost::shared_ptr<Base>, std::allocator<boost::shared_ptr<Base> > >::push_back(Base*&)' /usr/local/gcc-3.2.1/include/c++/3.2.1/bits/stl_vector.h:490: candidates are: void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = boost::shared_ptr<Base>, _Alloc = std::allocator<boost::shared_ptr<Base> >]

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Using boost::mutex in a boost::shared_ptr
by Anders Hybertz 17 Oct '03

17 Oct '03

Hi Can I store boost::mutex'es in a map using the following constuct typedef boost::shared_ptr<boost::mutex> MutexPtr; typedef map< std::string, MutexPtr> MutexMap; MutextMap mmap; mmap["foo"] = MutexPtr( new boost::mutex ); I'm not sure that this is safe to do - the boost::mutex is boost::noncopyable which might indicate that there could be a potentional problem. Thanks in advance

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Re: shared_from_this
by Dragan Milenkovic 16 Oct '03

16 Oct '03

> > >Date: Tue, 14 Oct 2003 16:02:25 +0300 >From: "Peter Dimov" <pdimov(a)mmltd.net> >To: "Boost Users mailing list" <boost-users(a)lists.boost.org> >Subject: Re: [Boost-users] shared_from_this > >Dragan Milenkovic wrote: > > >>Hello, people, >> >>I've been using enable_shared_from_this a LOT, mostly for implementing >>the Observer pattern (an object holds a list of weak pointers to it's >>observers). >> >> [snip] >>Also, any comments on the designs I used? Better observers? >> >> > >It is hard to say; you'll need to go into more detail about the observers. >If they are only notified on destruction of the observed entity, the typical >shared_ptr approach is to reverse/eliminate the dependency and make the >observers store weak pointers to the "observee". > >For other notification scenarios, there is the usual tradeoff between >polling and messaging. I prefer polling most of the time since this >eliminates the need to store an observer list and makes it possible to >"observe" classes that weren't specifically designed for this, but there may >be a performance cost. > > Well this (new) question is about observers in general, concurrent programming and C++. I believe to be making my way up the learning curve, but this seems to be a bit of problem. The proper destruction... Here is what I've been thinking. First the destruction of the subject (observee). As proposed in "Design Patterns", the subject could notify the observers about being destroyed, so the observers can handle that situation. But in my (more or less limited) experience, most often the observer is the one that controls the life-time of the subject (possibly by the means of shared_ptr). So this really presents no problem... But how to synchronize the destruction of the observer with a nofication originating from another thread? The observer's destructor would most likely perform Subject::unregister... But a call to Observer::update might have already been dispatched... The possible solutions I can think of are: 1. Make Subject::unregister have a postcodition stating that the observer will receive notifications no more (as of the moment the function returns). The words that come into my mind while thinking of possible implementations are: mutex, condition, dead-lock, inconsistency... What should the observer be allowed to do from inside the update function? Inspect only? I guess that could work... 2. Subject holds weak_ptr<Observer> and removes dead observers. I like it because of simplicity, but it (possibly) requires that Observer inherits enable_shared_from_this. In my design, the subject usualy passes a pointer to itself in the Observer::update method... Better yet - a shared_ptr, as it is more clean to compare shared pointer, especially inside the container. And how does it get shared_ptr to itself? shared_from_this() again. Is it really necessary? Although it does make the code easier to maintain. I might be wrong, but I get the impression that there is not much information on multithreading and destruction in C++. Destruction the way it is, makes C++ my language of preference. The lectures usually starts with a queue or a buffer with one mutex and one (or two) conditional variables, but it doesn't get any better. How is the queue destroyed? What about consumer which is waiting on a conditional variable? What is the common way of dealing with all this? Java-like interrupt? That's basically what I've been doing. Many thanks, Dragan Milenkovic

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ublas - solving linear systems
by sashan 15 Oct '03

15 Oct '03

I was looking for a way to solve a linear system using ublas and came upon this thread http://article.gmane.org/gmane.comp.lib.boost.user/1632 So does this mean I have to decompose my matrix? Can I do it using ublas?

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Re: [Boost-users] Inconsistency in graph Example Code, Documentation
by Jeremy Siek 15 Oct '03

15 Oct '03

Hi Thomas, Thanks for the bug report. Since the BGL book uses '-', and I can't change that, I've instead change the documentation and source file to also use '-' instead of '_'. Cheers, Jeremy On Tue, 14 Oct 2003, Thomas F. O'Connell wrote: tfo> This is a minor point but one worth correcting for the sake of tfo> correctness and ease of following the examples. tfo> tfo> In the boost-1.30.2 distribution, the file tfo> tfo> libs/graph/example/kevin-bacon.cpp tfo> tfo> makes a reference to a "./kevin-bacon.dat" file, but the file in both tfo> the distribution and the documentation is actually kevin_bacon.dat. tfo> tfo> The only difference being '_' vs. '-'. tfo> tfo> This is easily fixed by an end-user, but it would be nice to have the tfo> examples work out of the box. tfo> tfo> -tfo ---------------------------------------------------------------------- Jeremy Siek http://php.indiana.edu/~jsiek/ Ph.D. Student, Indiana Univ. B'ton email: jsiek(a)osl.iu.edu C++ Booster (http://www.boost.org) office phone: (812) 855-3608 ----------------------------------------------------------------------

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Missing default constructor for shared_count?
by Andrew Duncan 14 Oct '03

14 Oct '03

At line 109 of share_ptr (version 1.30.2) is the init list shared_ptr(): px(0), pn() which uses the default constructor for pn, which has type shared_count. However, there appears to be no such default constructor in shared_count. Am I missing something? Andrew P.S.: Forgive me if the answer appears somewhere easily searchable. I was unable to find an archive for bug reports or for this list. Pointers to such resources will be welcome.

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How to know wheter a Boost.thread has ended ?
by Huck finn 14 Oct '03

14 Oct '03

Hi, I need a way to find out if the threads that I created are done or not. I'm creating a somekind of thread_group that must clean the threads that have ended from the vector that keeps the threads within. void function () {} void main () { boost::thread thrd1(&function); //I'd need a function here to tell me that the thread has ended... if(thread1.IsDone()) { ... } } How can I do such a thing, any ideas? Thanks, Simon _________________________________________________________________ MSN Search, le moteur de recherche qui pense comme vous ! http://fr.ca.search.msn.com/

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RE: [Boost-users] Regex++ multiline matching
by Ben Hutchings 14 Oct '03

14 Oct '03

I wrote: > John Maddock <john(a)johnmaddock.co.uk> wrote: > > > I see that Regex++ always treats ^ and $ as start and end of line > > > rather than start and end of buffer. Perl does this only if the > > > /m switch is used. Is there a simple way to switch between these > > > two interpretations when compiling a regex? > > > > No but you can use \A and \z for that purpose. > > I know that, but I want to be able to interpret user-supplied regexes > either way. Maybe I can pre-process them to substitute ^ and $, but > that seems awkward. Alternately I could have the traits object return different interpretations for them, but that would require either: - switching between two specialisations of reg_expression at run-time (resulting in code bloat) or - changing reg_expression's constructors to allow the client to pass a traits object into it rather than always using the default constructor (unusual usage of a traits class)

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RE: [Boost-users] Regex++ multiline matching
by Ben Hutchings 14 Oct '03

14 Oct '03

John Maddock <john(a)johnmaddock.co.uk> wrote: > > I see that Regex++ always treats ^ and $ as start and end of line > > rather than start and end of buffer. Perl does this only if the /m > > switch is used. Is there a simple way to switch between these two > > interpretations when compiling a regex? > > No but you can use \A and \z for that purpose. I know that, but I want to be able to interpret user-supplied regexes either way. Maybe I can pre-process them to substitute ^ and $, but that seems awkward.

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shared_from_this
by Dragan Milenkovic 14 Oct '03

14 Oct '03

Hello, people, I've been using enable_shared_from_this a LOT, mostly for implementing the Observer pattern (an object holds a list of weak pointers to it's observers). I wanted to know why are shared_from_this member functions public instead of being protected? Also, I've used the following expression a few times: shared_polymorphic_cast<This>(shared_from_this()) Any thoughts on putting it inside the enable_shared_from_this... shared_from_base<This>() or polymorphic_shared_from_this<This>() or such? Also, any comments on the designs I used? Better observers? Best regards, Dragan Milenkovic

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Regex++ multiline matching
by Ben Hutchings 14 Oct '03

14 Oct '03

I see that Regex++ always treats ^ and $ as start and end of line rather than start and end of buffer. Perl does this only if the /m switch is used. Is there a simple way to switch between these two interpretations when compiling a regex?

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boost::function compilation
by Terence Ou 14 Oct '03

14 Oct '03

Hi, I'm currently trying to use boost::function with VC++ 7.0 and I get the compilation error stating that function is not a member of boost. I've already included the header <boost/function.hpp> as well as the library path in the project settings but it just doesn't seem to be able to compile. The documentation specifies things about the preferred and portable syntax. Is there even some setting choose the desired syntax, becoz there are no hints or instructions that mention anything on it in the the documentation and I can't find anything in the source files as well. Thanks. Cheers, Terence

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[BLL] bind(data_member_ptr,_1) functor won't accept temporaries as arguments
by Eelis van der Weegen 13 Oct '03

13 Oct '03

When Lambda's bind() is used to create a functor for dereferencing a stored data member pointer given an instance pointer, it seems it is not possible to pass the resulting functor a temporary instance pointer. For example: #include <boost/lambda/bind.hpp> #include <boost/lambda/lambda.hpp> struct S { int i; }; S * f (); void g (S * p) { using namespace boost::lambda; bind(&S::i, _1)(p); // ok bind(&S::i, _1)(p + 0); // not ok, "no match for call ..." bind(&S::i, _1)(f()); // not ok, "no match for call ..." } Does this restriction have a purpose? If not, is this something that needs to be (and can be) fixed? Regards, Eelis van der Weegen

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enable_shared_from_this::_internal_weak_this initialization
by Cody Batt 13 Oct '03

13 Oct '03

Hello, It seems that classes which inherit from enable_shared_from_this are required to explicitly initialize _internal_weak_this. 1) Is that correct? If not, how is it initialized? 2) Is this detail mentioned anywhere in the documentation? (I couldn't find it.) Thanks, Cody

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Stubbing for unit testing, what approach should I use
by Andrew Syrov 10 Oct '03

10 Oct '03

I am looking for set of techniques for isolation testing. As applications are designed with massive number of dependencies between classes and these dependencies end-up in external systems such as databases and OS, it's hard to extract function or part of class for efficient unit test. Basically I need an advice on what coding techniques should be used to allow flexible (generic?) stubbing: - function of a class may need to be tested in isolation from world (members could be global data for the purpose) - class may be tested with stubbed set functions; - data members could be stubbed, so no dependensies on classes which do not participate in test; Please advice. Andrew. _________________________________________________________________ Compare Cable, DSL or Satellite plans: As low as $29.95. https://broadband.msn.com

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Enhancement to shared_pointer to support pointers to contained objects.
by Ricardo Capurro 09 Oct '03

09 Oct '03

Hello, We are really very happy and impressed with boost's smart_pointers, and we found the section "Smart Pointer Programming Techniques" (http://www.boost.org/libs/smart_ptr/sp_techniques.html) in boost smart_pointer documentation very useful, but we are having this problem: We have two classes X and Y, and each object of class X holds an object of class Y, and we need to implement a method in class X to get a shared_ptr<Y> so we can access Y instance inside X, and we need that X objects (that are too referenced by shared_ptr<X>) don't be deleted until all references to the Y object are destroyed. See the problem in this code: class Y {}; class X : public enable_shared_from_this<X> { Y y; public: shared_ptr<Y> ptr_y(); // Oops, how do we do here??? }; Our first approach was "Using a shared_ptr to hold a pointer to a statically allocated object" (http://www.boost.org/libs/smart_ptr/sp_techniques.html#static) but this doesn't work because X objects can be destroyed and we still have pointers to contained Y object, so we try a custom deletor like this: template <typename Z> class delegator_deletor { shared_ptr<Z> ptr; // Internal pointer to father X, wich contains Y public: delegator_deletor( shared_ptr<Z> const & ptrz ) : ptr( ptrz ) {} template <typename T> void operator()( T* ) { ptr.reset(); } // Null deletor, only resets pointer to father X object }; template <typename Z> delegator_deletor<Z> make_delegator_deletor( shared_ptr<Z> ptrz ) { return delegator_deletor<Z>( ptrz ); } class X : public enable_shared_from_this<X> { Y y; public: shared_ptr<Y> ptr_y() { return shared_ptr<Y>( &y, make_delegator_deletor( shared_from_this() ) ); } }; And now the problem was resolved but with one little drawback, we are not sharing the same counter between shared_ptr<X> and shared_ptr<Y>, so start looking boost's code to shange it in a way that it satisfies our needs, and we added this constructor to shared_ptr class: template<class Y,class Z> shared_ptr(Y* y, shared_ptr<Z> const & z): px(z.px ? y : 0), pn( y ? z.pn : detail::shared_count() ) // never throws { detail::sp_enable_shared_from_this(y, y, pn); } then we change X::ptr_y() this way: shared_ptr<Y> X::ptr_y() { return shared_ptr<Y>( &y, shared_from_this() ); } This new constructor instructs to create a shared_ptr<> that uses the same counter that the second's shared_ptr<> parameter, but point's to the first raw pointer paramenter. With this change everithing worked fine. Finally our question is: Is there an easyer way to solve our problem? If the answer is yes we want to know it and if the answer is no we want to know if you can enhace shared_ptr to solve this kind of problem. Thank you very much Ricardo #include <iostream> #include <string> #include <boost/smart_ptr.hpp> #include <boost/enable_shared_from_this.hpp> using namespace ::std; using namespace ::boost; #if !defined( SOLUTION1 ) && !defined( SOLUTION2 ) && !defined( SOLUTION3 ) && !defined( SOLUTION4 ) #define SOLUTION3 #endif #if defined( SOLUTION1 ) class null_deleter { public: template <typename T> void operator()( T* ) {} }; #elif defined( SOLUTION2 ) || defined( SOLUTION3 ) template <typename Z> class delegator_deletor { shared_ptr<Z> ptr; public: delegator_deletor( shared_ptr<Z> const & ptrz ) : ptr( ptrz ) { cerr << "delegator_deletor<" << typeid( Z ).name() << ">()" << endl; } template <typename T> void operator()( T* ) { ptr.reset(); cerr << "delegator_deletor<" << typeid( Z ).name() << ">()( " << typeid( T ).name() << "* )" << endl; } }; template <typename Z> delegator_deletor<Z> make_delegator_deletor( shared_ptr<Z> const & ptrz ) { return delegator_deletor<Z>( ptrz ); } #endif class Y : public enable_shared_from_this<Y> { Y( Y const & ); Y& operator=( Y const & ); public: Y() { cerr << "Y::Y()" << endl; } ~Y() { cerr << "Y::~Y()" << endl; } }; class X : public enable_shared_from_this<X> { Y y; int i; X( X const & ); X& operator=( X const & ); public: X() : y(), i( 7 ) { cerr << "X::X()" << endl; } ~X() { cerr << "X::~X()" << endl; } shared_ptr<Y> ptr_y() { #if defined( SOLUTION1 ) return shared_ptr<Y>( &y, null_deleter() ); #elif defined( SOLUTION2 ) return shared_ptr<Y>( &y, make_delegator_deletor( shared_from_this() ) ); #elif defined( SOLUTION3 ) shared_ptr<Y> py; try { py = y.shared_from_this(); } catch ( const bad_weak_ptr& ) { py.reset( &y, make_delegator_deletor( shared_from_this() ) ); } return py; #elif defined( SOLUTION4 ) return shared_ptr<Y>( &y, shared_from_this() ); #endif } shared_ptr<int> ptr_i() { #if defined( SOLUTION1 ) return shared_ptr<int>( &i, null_deleter() ); #elif defined( SOLUTION2 ) || defined( SOLUTION3 ) return shared_ptr<int>( &i, make_delegator_deletor( shared_from_this() ) ); #elif defined( SOLUTION4 ) return shared_ptr<int>( &i, shared_from_this() ); #endif } }; int main( const int, const char** ) { try { cerr << "(1)" << endl; shared_ptr<X> px( new X() ); cerr << "(2)" << endl; shared_ptr<Y> py = px->ptr_y(); cerr << "(3)" << endl; shared_ptr<int> pi = px->ptr_i(); cerr << "(4)" << endl; px.reset(); cerr << "(5)" << endl; py.reset(); cerr << "(6)" << endl; pi.reset(); cerr << "(7)" << endl; } catch ( const exception& e ) { cerr << "Exception caught: " << e.what() << endl; } catch ( ... ) { cerr << "Exception caught ..." << endl; } return 0; }

2 1

Re: [Boost-users] Re: Problem using Boost.thread : Class destructor calledseveral times!
by Huck finn 08 Oct '03

08 Oct '03

Ok, now I see that my object is being copied. But for the lines : FakeClass *item1 = new FakeClass(1);//,item2(2); group.create_thread(*item1); I get : FakeClass #1 says : I'm alive! FakeClass #1 says : Being Copied!! FakeClass #1 says : Being Copied!! FakeClass #1 says : Being Copied!! FakeClass #1 says : I'm being destroyed! FakeClass #1 says : I'm being destroyed! FakeClass #1 says : Being Copied!! FakeClass #1 says : I'm being destroyed! Thread for FakeClass #1 has been started! FakeClass #1 says : I'm being destroyed! main ending... The copy constructor is called 4 times!!! And it is called 3 times before the thread has even started! Is there a way to avoid that ? I was going to use the thread_group to manage the connection to a simple server applications, so that all the threads would hold info about the socket used for connection, etc... And that if the objectdestructor is called, the connection to the socket would be closed... With my object being destroyed 3 times before the thread has started, it gets a bit hard to manage that way... Any clue on how to use the threads so that it would work? thanks, Simon _________________________________________________________________ MSN Messenger : discutez en direct avec vos amis ! http://messenger.fr.msn.ca/

2 1

Re: compiler warnings...
by David Abrahams 08 Oct '03

08 Oct '03

David Ohlemacher <ohlemacher(a)bbn.com> writes: > Hi all from a boost newbie, > > Given: > Linux RH 8.0 > gcc 3.2 > BOOST_VERSION 103002 > > I created a boost app and it compiles and runs however I am getting > lots of warnings of the form > /usr/lib/boost/boost/iterator_adaptors.hpp:775:43: warning: > "BOOST_MSVC" is not defined. > > What am I not doing correctly? You're using -Wall ;-) We're currently discussing what to do about these warnings on the developers' list. Stay tuned, and until then turn off -Wall or live with the warnings. Sorry, -- Dave Abrahams Boost Consulting www.boost-consulting.com

3 2

compiler warnings...
by David Ohlemacher 08 Oct '03

08 Oct '03

Hi all from a boost newbie, Given: Linux RH 8.0 gcc 3.2 BOOST_VERSION 103002 I created a boost app and it compiles and runs however I am getting lots of warnings of the form /usr/lib/boost/boost/iterator_adaptors.hpp:775:43: warning: "BOOST_MSVC" is not defined. What am I not doing correctly? I have both included and not included <boost/config.hpp> and I read (http://www.boost.org/libs/config/config.htm#header) that I should not include this. Thanks, -d

1 0

mpl + enum + VC = error
by nagual 06 Oct '03

06 Oct '03

Hello, All! I write simple code: =============mpl_enum.cpp============= #include <boost/mpl/range_c.hpp> #include <boost/mpl/for_each.hpp> #include <iostream> enum test_e {ONE, TWO, THREE}; void f(test_e e) { const char* names[] = {"ONE", "TWO", "THREE"}; std::cout<<names[e]<<std::endl; } typedef boost::mpl::range_c< test_e, ONE, static_cast<test_e>(THREE + 1) > range; int main() { boost::mpl::for_each<range>(f); return 0; } =============mpl_enum.cpp============= MSVC 7 (ver 13.00.9466) =============Command Line============== c:\cl /EHsc /GR /Zc:wchar_t /Zc:forScope /nologo mpl_enum.cpp =============Command Line============== =============Output===================== mpl_enum.cpp C:\Lang\Projects\boost\boost\mpl\aux_\integral_wrapper.hpp(78) : error C2440: 'return' : cannot convert from '' to 'test_e' Conversion to enumeration type requires an explicit cast (static_cast, C-style cast or function-style cast) C:\Lang\Projects\boost\boost\mpl\aux_\integral_wrapper.hpp(78) : while compiling class-template member function 'boost::mpl::integral_c<T,N>::operator`T'(void) const' with [ T=test_e, N=ONE ] C:\Lang\Projects\boost\boost\mpl\aux_\range_c\iterator.hpp(34) : see reference to class template instantiation 'boost::mpl::integral_c<T,N>' being compiled with [ T=test_e, N=ONE ] C:\Lang\Projects\boost\boost\mpl\for_each.hpp(70) : see reference to class template instantiation 'boost::mpl::range_c_iterator<N>' being compiled with [ N=boost::mpl::range_c<test_e,ONE,3>::start ] C:\Lang\Projects\boost\boost\mpl\for_each.hpp(101) : see reference to function template instantiation 'void boost::mpl::aux::for_each_impl<done>::execute(Iterator *,last *,transform_op *,void (__cdecl *)(test_e))' being compiled with [ done=false, Iterator=first ] C:\Lang\Projects\boost\boost\mpl\for_each.hpp(111) : see reference to function template instantiation 'void boost::mpl::for_each(F,range *,boost::mpl::identity<T> *)' being compiled with [ F=void (__cdecl *)(test_e), T=boost::mpl::void_ ] mpl_enum.cpp(15) : see reference to function template instantiation 'void boost::mpl::for_each(F,range *)' being compiled with [ F=void (__cdecl *)(test_e) ] =============Output===================== However gcc v3.2.3, icl v 7.1, bcc32 v5.6.4 compile it. (bcc32 show 3 equivalent warning). How use it in MSVC 7?

2 1

remove_pointer
by Leo Landa 05 Oct '03

05 Oct '03

Good day to everyone, I am trying to find a portable enough implementation of remove_pointer (MSVC 6, MSVC 7.1, G++ 2.95.3, G++ 2.96). The "usual" template technique relies on partial template specialization, which MSVC 6.0 does not support. As far as I can tell, Boost's version of remove_pointer is a little bit of a "cheat" - i.e. it becomes predefined only for primitive types. Am I right about that? I'm a bit of a newb in these parts of London ;-) If this is true, then I'm screwed - and I can't convert a generic pointer type to the pointee type. If it is not true, then what is the technique? Leo. P.S. Just in case - I know how to figure out _whether_ the type is a pointer, and now just trying to strip it.

2 2

iterators
by Witz 05 Oct '03

05 Oct '03

Hi, I would like to raise a couple of points about the iterator adaptors. Firstly, is it really necessary to have the predicate as part of the template specification for the filter_iterator? Surely it can be assumed that it will always be convertible to boost::function<bool (const value_type&)> ? Secondly, by allowing the return type of the function used by the transform_iterator to be a reference can we not use it to implement a more generic form of indirect_iterator? The code below gives a flavour of the idea. struct dereference { typedef int result_type; int* data_; dereference(int* data):data_(data){} int operator()(int i) const { return data_[i]; } }; int main() { int data[] = { 1,2,3,4,5,6,7,8 }; int keys[] = { 0,3,1,6,5,4,2,7 }; typedef boost::transform_iterator_generator<dereference, int*>::type indirect_iterator; indirect_iterator i(keys, dereference(data)), i_end(keys+8,dereference(data)); while(i != i_end) std::cout << *i++ << ' '; return 0; } The output is: 1 4 2 7 6 5 3 8 Witz

3 2

boost library build consistency
by Thomas S. Urban 03 Oct '03

03 Oct '03

Is there any definition of how libraries are supposed to build? I've integrated the building of required boost libraries into the build system for our projects. There seems to be some inconsistency in what gets built and where it gets put. In particular, for the thread and regex libs, boost builds both shared and static versions of the libraries and puts them in a bin-stage subdirectory under the library build directory. However, for the filesystem library, only the static library gets built and the bin-stage/ directory is not used. Is there a standard behavior library developers are supposed to follow in this regard? Can I count on the bin-stage/ as a short-named location for the most recent build of any library? Are the boost or boost_filestsystem maintainers interested in the simple fix to the Jamfile to make that library behave like the other two I mentioned? Thanks Scott Urban

3 3

parse error in format library
by Alan Stewart 03 Oct '03

03 Oct '03

I've been successfully using the tokenizer library for some time, and am very grateful for it. The format library looks very userful - I need to convert a bunch of old printf's to ostreams. However, in attempting to compile with gcc 2.96 I'm finding that there are many substitutions that need to be made, such as replacing "char_traits" with "basic_string". I'm using Boost 1.30.0 in production, but have also tried 1.30.2 with the same results. I see that the format library headers include the header file "boost/config.hpp". Is it likely that I have some sort of configuration error? Where do I find information on toolset compatabiliy for specific Boost libraries, since this one does not seem to be compatible with mine? -- D. Alan Stewart Senior Software Developer Layton Graphics, Inc. 155 Woolco Drive Marietta, GA 30065 Voice: 770/973-4312 Fax: 800/367-8192 http://www.layton-graphics.com

2 1

Problem using Boost.thread : Class destructor called several times!
by Huck finn 02 Oct '03

02 Oct '03

Hi there, still a newbie question for you guys... I changed a bit the sample example from thread.cpp : here's the new code i'm trying: ----------------- boost::mutex io_mutex; // The iostreams are not guaranteed to be thread-safe! class FakeClass { public: FakeClass(int NewID):ID(NewID) { boost::mutex::scoped_lock scoped_lock(io_mutex); std::cout<<"FakeClass #"<<ID<<" says : "<<"I'm alive!"<<std::endl; } ~FakeClass() { boost::mutex::scoped_lock scoped_lock(io_mutex); std::cout<<"FakeClass #"<<ID<<" says : "<<"I'm being destroyed!"<<std::endl; } void operator()() { boost::mutex::scoped_lock scoped_lock(io_mutex); std::cout<<"Thread for FakeClass #"<<ID<<" has been started!"<<std::endl; } private: int ID; }; void main () { boost::thread_group group; FakeClass item1(1),item2(2); group.create_thread(item1); group.create_thread(item2); group.join_all(); std::cout<<" main ending..."<<std::endl; } ----------------------------- here's what I get when executing : FakeClass #1 says : I'm alive! FakeClass #2 says : I'm alive! FakeClass #1 says : I'm being destroyed! FakeClass #1 says : I'm being destroyed! FakeClass #1 says : I'm being destroyed! Thread for FakeClass #1 has been started! FakeClass #2 says : I'm being destroyed! FakeClass #1 says : I'm being destroyed! FakeClass #2 says : I'm being destroyed! FakeClass #2 says : I'm being destroyed! Thread for FakeClass #2 has been started! FakeClass #2 says : I'm being destroyed! main ending... FakeClass #2 says : I'm being destroyed! FakeClass #1 says : I'm being destroyed! Press any key to continue 1- I'm wondering why the destructor of my FakeClass is called 4 times for each items ??? 2- It says in the doc that the function that creates a thread "copies the function wrapped by threadfunc" and threadfunc would be in this case item1 and item2, does this means that the copy constructor is called every time a thread is created with an object? Thanks all! Simon _________________________________________________________________ MSN Messenger : discutez en direct avec vos amis ! http://messenger.fr.msn.ca/

3 2

Problem with is_class and is_enum
by Romain Lerallut 02 Oct '03

02 Oct '03

In the following code, struct foo2 is mistakenly taken for an enum, which breaks is_class, which leads to some unfortunate problems in boost::python. Problem appears on both Boost 1.30.0 and a one-month old CVS checkout, using gcc 3.3.2 and 2.95 and Intel icc 7.1 for linux. I have tried specializing 'is_enum', setting it by hand to return 'false', but though it works for this simple case, it does no good when the call to is_enum is buried deep inside boost. I rely heavily on being able to do these implicit conversions for foo2, so if anyone has an idea on how to make this work, it would be great. Thanks in advance, Romain ---------------------------------------------------------------- #include <boost/type_traits/is_enum.hpp> #include <iostream> struct foo1 // this one is not detected as an enum { operator int() { return 0; } }; struct foo2 // this one *is* detected as an enum { template<typename T> operator T(){return 0;} }; int main() { std::cout<<boost::is_enum<int>::value<<"\n"; std::cout<<boost::is_enum<foo1>::value<<"\n"; std::cout<<boost::is_enum<foo2>::value<<"\n"; } -------------------------------------------------------------- Expected Result: 0 0 0 Actual Result: 0 0 1

2 1

compilation on Win64 platform with MSVC7.1 for 64 bit
by bart.tanghe＠skynet.be 02 Oct '03

02 Oct '03

Hi, we're using Boost 1.30.0 with MSVC7.1 on a Win32 platform. Currently where working on a port to a Win64 platform using the MSVC7.1 for IA64 compiler. (13.10.2240.8 for IA64) I just compiled the code as is and unfortunately I encountered errors in boost headers. This probably is because of missing/bad defines for this 'unknown' platform in the config headers... I was wondering if somebody already tried to compile boost on a 64 bit platform, and if he/she succeeded? Or if there are known implementation details which would cause boost 'never' to work on 64 bit platforms? If there are no known 'showstoppers' then I suppose I'll have to go through the Boost Configuration Reference or should I look somewhere else? Thanks, Bart

2 1

Compile Boost.thread libraries has a static library (.lib) with msvc 6 ?
by Huck finn 01 Oct '03

01 Oct '03

Hi everyone, I'm a total newbie to boost, but I've got to developp a project that could use some of the powerful boost libraries, so I'm trying to make a move in that way... Ok, most of the boost libraries I can build in a static way and create (.lib) files with Microsoft Visual Studio 6.0 for my partners to use . But I am having a problem doing the same thing with the Boost.Thread libraries... First question : Is it possible to build this librairy in a (.lib) file with msvc 6.0? I'm getting tons of warnings concerning "dllexport" problems, but the (.lib) are still created. I was wondering if someone could help me understanding/fixing the warning problems : warning C4275: non dll-interface class 'boost::noncopyable' used as base for dll-interface class 'boost::detail::condition_impl' c:\wrk\common\boost-1.30.2\boost\noncopyable.hpp(22) : see declaration of 'noncopyable' warning C4273: 'thread::thread' : inconsistent dll linkage. dllexport assumed. I really need to avoid using .dll in this project, so builing this static library is very important to me... Thanks in advance, Simon _________________________________________________________________ MSN Search, le moteur de recherche qui pense comme vous ! http://fr.ca.search.msn.com/

5 7

bind and Constructor invocation?
by Jeff Flinn 30 Sep '03

30 Sep '03

I don't see any way to use bind to directly construct an object, other than calling a function that returns an object. Or am I missing something? Like something similar to Spirit::Phoenix construct_<>? This would avoid manually creating these factory functions. -- Jeff Flinn Applied Dynamics, International

1 0

BGL runtime crash with g++ -O2 optimizer.
by Franck.Caron＠infineon.com 29 Sep '03

29 Sep '03

Hi all, I have a problem while compiling BGL with gcc 3.1.1 on solaris7 with the -O2 optimizer option. All is ok with -g (debug) but -O2 produce a crash at runtime Here is a code that reproduce the problem : #include <boost/graph/adjacency_list.hpp> #include <boost/graph/properties.hpp> #include <iostream> #include <string> using namespace std; using namespace boost; struct VertexPropertyTag { typedef vertex_property_tag kind; }; typedef property<VertexPropertyTag,string> VertexProp; typedef adjacency_list<setS,vecS,bidirectionalS,VertexProp> Graph; int main(){ Graph graph; graph_traits<Graph>::vertex_descriptor v1 = add_vertex(string("s1"),graph); graph_traits<Graph>::vertex_descriptor v2 = add_vertex(string("s2"),graph); add_edge(v1,v2,graph); graph_traits<Graph>::edge_iterator eIt,eItEnd; tie(eIt,eItEnd) = edges(graph); for(;eIt != eItEnd;++eIt){ cout << "->" << *eIt << endl; } return 0; } With g++ -Wall -pedantic -fPIC -g -c -o solaris7/gcc3.1/Main.o Main.cc -I. -I/opt/boost_1.30.2 g++ -fPIC -o solaris7/gcc3.1/testbug.exe solaris7/gcc3.1/Main.o -L /opt/boost_1.30.2/libs/gcc3.1/release/single-thread -R -Wl,-Bdynamic Here is the result : shell> solaris7/gcc3.1/testbug.exe ->(0,1) It is OK With g++ -Wall -pedantic -fPIC -O2 -c -o solaris7/gcc3.1/Main.o Main.cc -I. -I/opt/boost_1.30.2 g++ -fPIC -o solaris7/gcc3.1/testbug.exe solaris7/gcc3.1/Main.o -L /opt/boost_1.30.2/libs/gcc3.1/release/single-thread -R -Wl,-Bdynamic Here is the result : shell> solaris7/gcc3.1/testbug.exe ->(0,1) ->(0,0) Bus error (core dumped) Does anybody already had this ? Is it a bug in my code, in BGL or in gcc ? Thanks for the help. Franck

1 0

Re: [Boost-users] Trying to get boost threads working under visual .NET
by John Maddock 29 Sep '03

29 Sep '03

> I'm trying to get the Boost thread library working under Microsoft .Net, > here is what I've done and the problems I'm seeing. > > I am currnetly using the regex lib and the date/time classes, which are > working. I now want to start creating threads so I follow the given > example, and started to get linker errors for xtime_get and > boost::thread::sleep. So I look around, and do the bjam -sTOOLS=msvc in > the appropriate threads directory and get no errors. It still won't > link. > I notice that the only boost*.lib files in my vc7\lib dir were from > boost_regexp, so I copy 4 files boost_thread(d).dll/lib into that > directory. I then explicitely add boost_threadd.lib into the project's > link. Ok, so now my application compiles AND links, but it wants > boost_threadd.dll when it executes. So I copy boost_threadd.dll into the > projects Debug directory wehre the .exe compiles to. Now when I run it, I > get a dialog box saying the application failed because > "boost_regex_vc7_mdid.dll" can not be loaded! the regex stuff was working > FINE and I don't think I did anyhting to change it. > > So can someone shed some light on this for me, please ? Why does it now > want the boost_regex dll? Thanks for any input.. if I've missed some > crucial documentation somewhere, sorry. If you changed your project build options from using one of the static C runtimes to using the dll runtime then that would be the problem, define BOOST_REGEX_STATIC_LINK when building if you want to static link to boost.regex. John. --------------------------------- Want to chat instantly with your online friends? Get the FREE Yahoo!Messenger

1 0

regex and stream processing
by John Maddock 29 Sep '03

29 Sep '03

Message forwarded from Dave Gomboc: > We have a stream of text data (actually it is a chunked > response of a webserver, but it might be a file or > something...) The data size may be very large and we need to > do some find/replace in this stream using regular > expressions. It is not possible to load entire stream into > the memory. I'm not even hope that Regex++ could work with > such kind of streams, but maybe someone can suggest me a > solution to this problem? This is possible without much trouble _if_ the text strings you are trying to match will fit into main memory, even if all the data won't. Use a std::list as a buffer, so that deleting and inserting is inexpensive, and you don't have to perform copies and update iterators when reading in more input. Fill your (sliding window) buffer, then regex it, using the partial match feature whenever you have not already detected the end of the file. If a match occurs, any characters occuring before the match can be processed (serialized to disk, or whatever) and removed from the buffer. Repeat this looking for a match until you reach the end of current input. You'll either have "no match" or "partial match" at this point: remove non-matching characters (that could be all of them) at this point, then re-fill your buffer with more data and keep going. If you're just doing one substitution, that's fine, but if more, there are a few things to keep in mind. I have done over 60 distinct substitutions at a time on a stream of 0.1 gigabytes using this technique, and it works quite quickly. (I used a buffer that held about 1 million characters (2^20), but I also tested with buffers as small as 256 characters -- the strings I was matching were not large). Just read in data, process all the substitutions in order, write the data out and repeat. If you're doing multiple substitutions, you (of course) can't flush any data from memory until you've tried all the substitutions on the current region of interest. Also, for each later substituion, the current region of interest shrinks because you have to acknowledge partial matches from earlier subsitutions. For example, say that there is no partial match at the end of substituions 1 through 6 (there might have been full matches where substitution was performed, that's okay.) But substituion 7 has a partial match at the last five characters. Now, your region of interest for substitution 8 is five characters smaller, because you don't want to process those last five characters because substitution 7 might change them once you've read in more input. The order of your substituions is important if the outputs of some desired subsitutions overlap with the inputs of others. If you are not grokking my meaning, I can fish around for the source code. Perhaps it's easier to explain in code than in words, my code for the entire process is maybe 10 or 15 lines. An alternative is to try to do some streambuf hacking, but the above method was simpler and adequate for my purposes. Dave --------------------------------- Want to chat instantly with your online friends? Get the FREE Yahoo!Messenger

1 0

regex problem
by John Maddock 29 Sep '03

29 Sep '03

> The last assert always fails, because regex::match insists on including the > space after the ":" in the second match result, which seems wrong to me. > I've tried giving various different combinations of flags to the regex ctor, > although from what I can tell from the documentation the default flags > should work. This is with VC7 and boost 1.30.2. For comparison, perl > (5.6.1) does not seem to have this problem, as the following script > illustrates: > > #!/usr/bin/perl > print "matches: <$1> <$2>\n" if ('foo: bar' =~ /([\w]+):[\s]*(.*)/); > > Is there any way to get the behavior I want? This is the difference between perl and POSIX leftmost-longest matching rules showing itself (the next release will default to perl rules and do what you want, but of course that doesn't help you now), basically non-marked sections are neither greedy nor non-greedy under POSIX rules, so regex finds the match it does because it makes $2 further to the left than the alternative (without effecting the overall match). You can get the effect you want by making your expression more "precise": "([\\w]+):[\\s]*([^\\s].*)" for example, John. --------------------------------- Want to chat instantly with your online friends? Get the FREE Yahoo!Messenger

1 0

Re: Implementation of my first template class
by Zenaan Harkness 29 Sep '03

29 Sep '03

Take 3: /** * A class providing a combination of an input stream * and an input iterator. * I use for convenience when processing a part-ascii, * part-binary stream. */ template<typename charT, typename traits = std::char_traits<charT> > class basic_istringtraverser : public std::basic_istringstream<charT, traits> { public: basic_istringtraverser(std::basic_string<charT> s) : std::basic_istringstream<charT, traits>(s) {} charT operator*() {return (charT)(rdbuf()->sgetc());} basic_istringtraverser& operator++() { rdbuf()->sbumpc(); return *this; } }; /** Specialization for char type. */ typedef basic_istringtraverser<char> istringtraverser;

1 0

RE: [Boost-users] Base Pointer member functions failure
by Mark Loew 29 Sep '03

29 Sep '03

Excellent thanks. I see exactly what I was missing. Thanks for the help. Mark Loew, MCSD, MCSE Application Development Consultant Sagestone Consulting www.sagestone.com Grand Rapids, MI 616-954-9556 x149 Microsoft Gold Certified Partner mloew(a)sagestone.com -----Original Message----- From: Douglas Gregor [mailto:gregod@cs.rpi.edu] Sent: Saturday, September 27, 2003 1:58 PM To: Boost Users mailing list Subject: Re: [Boost-users] Base Pointer member functions failure On Friday 26 September 2003 06:38 pm, Mark Loew wrote: > Alright I am now functioning in my code. > > Now the hard part. Can you explain to me what I am missing. The _1 > states to use the first paramter in the first position. > > Doug mentioned that there is an implicit 'this' argument. That was Peter :) > So the bind is creating a function object > template<class S, class T, class A> > With the constructor of > somefunc( S (T::*p)(A) ); // declaring the pointer to the function > > then the operator is > operator( T *p, A x ) > and calls the func Right, so the function object has two parameters, the first (which corresponds to the implicit 'this' parameter) is of type T* and the second is of type A. When using bind, think of member function pointers as having an operator() like this one, and try to forget the ugly member pointer syntax. > So in the bind I was thinking that > Boost::bind( Base::CheckFunc, x ) > > I wrongly assumed that the T value was the variable passed in by the > find_if and the second parameter was the x my second variable on my > func. With bind(), no parameter is special, including the implicit object parameter. If we have: g = boost::bind(f, _1, x) then g(y) maps to: f(y, x) in our case, 'f' is an adaptor around a member function pointer, which ends up calling: y->*CheckFunc(x) Doug _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Re: [Boost-users] istream U istream_iterator -> traverser
by Zenaan Harkness 28 Sep '03

28 Sep '03

Further thought: has anyone ever written (made available) something like <vstream> for streaming into and out of vectors (similar to <sstream>). Or perhaps <cstream> - generic container streaming in/out, with specializations for vector, etc. - or has such a thing just never been needed by anybody before? tia zen

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Trying to get boost threads working under visual .NET
by Brian Bowles 28 Sep '03

28 Sep '03

I'm trying to get the Boost thread library working under Microsoft .Net, here is what I've done and the problems I'm seeing. I am currnetly using the regex lib and the date/time classes, which are working. I now want to start creating threads so I follow the given example, and started to get linker errors for xtime_get and boost::thread::sleep. So I look around, and do the bjam -sTOOLS=msvc in the appropriate threads directory and get no errors. It still won't link. I notice that the only boost*.lib files in my vc7\lib dir were from boost_regexp, so I copy 4 files boost_thread(d).dll/lib into that directory. I then explicitely add boost_threadd.lib into the project's link. Ok, so now my application compiles AND links, but it wants boost_threadd.dll when it executes. So I copy boost_threadd.dll into the projects Debug directory wehre the .exe compiles to. Now when I run it, I get a dialog box saying the application failed because "boost_regex_vc7_mdid.dll" can not be loaded! the regex stuff was working FINE and I don't think I did anyhting to change it. So can someone shed some light on this for me, please ? Why does it now want the boost_regex dll? Thanks for any input.. if I've missed some crucial documentation somewhere, sorry.

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RE: [Boost-users] Base Pointer member functions failure
by Mark Loew 27 Sep '03

27 Sep '03

Alright I am now functioning in my code. Now the hard part. Can you explain to me what I am missing. The _1 states to use the first paramter in the first position. Doug mentioned that there is an implicit 'this' argument. So the bind is creating a function object template<class S, class T, class A> With the constructor of somefunc( S (T::*p)(A) ); // declaring the pointer to the function then the operator is operator( T *p, A x ) and calls the func So in the bind I was thinking that Boost::bind( Base::CheckFunc, x ) I wrongly assumed that the T value was the variable passed in by the find_if and the second parameter was the x my second variable on my func. What am I missing. I just don't want my code to work I want to know why. Makes reusing the thing much easier. Mark Loew, MCSD, MCSE Application Development Consultant Sagestone Consulting www.sagestone.com Grand Rapids, MI 616-954-9556 x149 Microsoft Gold Certified Partner mloew(a)sagestone.com -----Original Message----- From: Peter Dimov [mailto:pdimov@mmltd.net] Sent: Friday, September 26, 2003 6:11 PM To: Boost Users mailing list Subject: Re: [Boost-users] Base Pointer member functions failure Mark Loew wrote: > Okay, > > Call me stupid but I can't get this to work > > class Base > { > virtual const bool CheckFunc(const value& val ) const { return > true; } } [...] > std::find_if( vecBase.begin(), vecBase.end(), > boost::bind(Base::CheckFunc, aVal ) ); Try boost::bind(&Base::CheckFunc, _1, aVal) instead. Remember that a member function has an implicit 'this' argument. _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Building boost threads with MinGW
by Jeremy Godfrey 27 Sep '03

27 Sep '03

Hi, When I build boost threads with bjam and MinGW, the resulting DLL is not dependent on mingwm10.dll like (as I understand things) all MinGW multithreaded binaries should be. This would indicate that the -mthreads compile/link option is not being used. Does anyone know how to fix this? Regards, Jeremy Godfrey --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com) Version: 6.0.520 / Virus Database: 318 - Release Date: 18/09/2003

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istream U istream_iterator -> traverser
by Zenaan Harkness 27 Sep '03

27 Sep '03

Sidestepping any ascii/binary issues for the moment, I am reading a part-binary, part-ascii file(s) and needing to process them (extract their data). I have need to read characters, as well as read in "binary" numbers, and print the whole lot out as ascii, with delimiters, etc (I use a mini-program/ format-string as a 'driver' to specify to my program how to process the input). I eventually realised (after converting my code back and fort between iterator style and istream style) that in fact I need both an istream and an input iterator (conveinence factor here). So firstly, I created both an istringstream, and an istream_iterator over that istringstream. Using either to .get or >> extract stuff from my string/stream would advance the underlying buffer, so things seem to work out well. I then decided to combine the two into a single class, which I can then "hide" implementation details or add functionality (eg. manipulators to specify byte-oirdering, endianness, etc), and still have one nice big interface of stream + iterator to get stuff from. My question is, why did this initial cut not compile: using namespace std; class istringtraverser : public istringstream, public istream_iterator<char> { public: istringtraverser(string s) : istringstream(s), istream_iterator<char>(*this) {} }; While this one DOES compile: using namespace std; class istringtraverser : public istringstream, public istream_iterator<char> { istringstream* miss; public: istringtraverser(string s) : istringstream(s), miss(this), istream_iterator<char>(*miss) {} }; And, how can I instantiate my traverser without it segfaulting? Eg., on my debian box, "istringtraverser st(some_string);" compiles but segfaults. Any insight appreciated, Zenaan PS I'm a Java programmer learning C++, finding out that C++ is more powerful/ featureful, yet some simple things (eg. uppercase a std::string, using std::transform with std::toupper) just do not work as expected. I can see why they now teach Java as a first language at Uni.

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Base Pointer member functions failure
by Mark Loew 26 Sep '03

26 Sep '03

Okay, Call me stupid but I can't get this to work class Base { virtual const bool CheckFunc(const value& val ) const { return true; } } class Derived1: public Base { } class Derived2: public Base { } // some where else in code Derived1 dev1; Derived2 dev2; vector<Base *> vecBase; vecBase.push_back( &dev1 ); vecBase.push_back( &dev2 ); value aVal; vec<Base *> std::find_if( vecBase.begin(), vecBase.end(), boost::bind( Base::CheckFunc, aVal ) ); I have tried a gazillion things a thought would work using mem_fun_ref and such. This ones get's me the closest I believe but I get a bunch of qualifier to funcation type has no meaning warnings. As well I get a condiation expression of type 'overloaded-function is illegal. I am using VS.Net 2003. Any ideas on what I am missing. As well can I get my cake and eat it to by making the CheckFunc virtual and have it resolve to the derived form? TIA Mark Loew, MCSD, MCSE Application Development Consultant Sagestone Consulting www.sagestone.com <http://www.sagestone.com/> Grand Rapids, MI 616-954-9556 x149 Microsoft Gold Certified Partner mloew(a)sagestone.com

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boost regex and match_partial
by Angus Leeming 26 Sep '03

26 Sep '03

I'm afraid I haven't got the hang of match_partial. Below is a little code with two functions that I think should produce identical results, but don't. In strip_commas_try1 I use: boost::regex const front("^( *[[],*)(.*)$"); regex_match(it, end, what, front); In strip_commas_try2 I use: boost::regex const front("^( *[[],*)"); regex_match(it, end, what, front, boost::match_partial); Why does this second case not result in what[0].matched ? Many thanks, Angus (This is with BOOST_VERSION 103002 and g++ (GCC) 3.2 20020903 (Red Hat Linux 8.0 3.2-7)). #include<iostream> #include<string> #include <boost/regex.hpp> using std::string; string const strip_commas_try1(string const & input) { string::const_iterator it = input.begin(); string::const_iterator end = input.end(); // Strip any commas that follow immediately after the '['. // "[,,,,foo..." -> "foo..." boost::regex const front("^( *[[],*)(.*)$"); boost::smatch what; regex_match(it, end, what, front); if (!what[0].matched) { std::cout << "Try 1 failed" << std::endl; return string(); } it = what[1].second; string const result = string(it, end); std::cout << "Try 1: " << result << std::endl; return result; } string const strip_commas_try2(string const & input) { string::const_iterator it = input.begin(); string::const_iterator end = input.end(); // Strip any commas that follow immediately after the '['. // "[,,,,foo..." -> "foo..." boost::regex const front("^( *[[],*)"); boost::smatch what; regex_match(it, end, what, front, boost::match_partial); if (!what[0].matched) { std::cout << "Try 2 failed" << '\n'; return string(); } it = what[1].second; string const result = string(it, end); std::cout << "Try 1: " << result << std::endl; return result; } int main() { string const input = "[,,,foo,,,,bar,,,gaz,,]"; std::cout << "Input: " << input << std::endl; strip_commas_try1(input); strip_commas_try2(input); return 0; }

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indirect_iterator_generator and std::distance ambiguity
by Jeff Flinn 24 Sep '03

24 Sep '03

I'm having problems compiling the code below with boost_1_30_2 and VC71 complaining about: ...\Microsoft Visual Studio .NET 2003\Vc7\include\xutility(489) : error C2665: 'std::_Distance2' : none of the 4 overloads can convert parameter 4 from type 'std::iterator_traits<_Iter>::iterator_category' with [ _Iter=CDictionary::tVarConstItr ] ... Replacing with std::distance( lBeg.base(), lItr.base() ) does compile and work properly. Am I missing something in the typedef of tVarConstItr that would allow direct usage? ---------------------------------------------------------- class CDictionary { ... class VarSpec { ... typedef boost::shared_ptr<VarSpec> tPtr; }; typedef VarSpec tVar; typedef tVar::tPtr tVarPtr; typedef std::vector<tVarPtr> tVars; typedef boost::indirect_iterator_generator < tVars::const_iterator , tVar , tVar& , tVar* , std::iterator_traits<tVars::const_iterator> ::iterator_category >::type tVarConstItr; typedef boost::indirect_iterator_generator < tVars::iterator , tVar , tVar& , tVar* , std::iterator_traits<tVars::iterator> ::iterator_category >::type tVarItr; tGroups Groups()const{ return mGroups; } tVarItr VarBegin() { return tVarItr ( mVars.begin() ); } tVarItr VarEnd () { return tVarItr ( mVars.end () ); } tVarConstItr VarBegin()const{ return tVarConstItr( mVars.begin() ); } tVarConstItr VarEnd ()const{ return tVarConstItr( mVars.end () ); } }; usage: ------ int CDictionaryEditorView::Idx( const TCHAR* aChrPtr, bool aExact )const { boost::function1<bool,const CDictionary::VarSpec&> lFindFnc; if( aExact ) { lFindFnc = boost::bind( std::equal_to<std::string>() , std::string(aChrPtr) , boost::bind( &CDictionary::VarSpec::Name, _1 ) ); } else { //... } CDictionary::tVarConstItr lBeg = mDctPtr->VarBegin(); CDictionary::tVarConstItr lEnd = mDctPtr->VarEnd (); CDictionary::tVarConstItr lItr = std::find_if( lBeg, lEnd, lFindFnc ); return (lItr!=lEnd)? std::distance( lBeg, lItr ) : -1; } -- Jeff Flinn Applied Dynamics, International

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[bgl] how to reverse a graphvizDigraph?
by Jeremie Leguay 24 Sep '03

24 Sep '03

Hi! I would like to reverse all the edges of a graphviz graph but the structure of this kind of graph doesn't seems to fit with the one use by the reverse_graph functionalities. Am I true or did I forget something? Here is the code that doesnt work: GraphvizDigraph g; read_graphviz("datas",g); typedef reverse_graph<GraphvizDigraph> ReverseGraphType; ReverseGraphType gr(g); print_graph(gr, get(vertex_index, gr)); //if I remove this line, it works! More generally, I would like to inverse the graph with keeping the same indexes on the vertices. Do you have ideas? best regards /Jeremie Leguay

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regex problem
by Scott McCaskill 24 Sep '03

24 Sep '03

I seem to be having some trouble with the regex library: #include <boost/regex.hpp> #include <cassert> #include <iostream> int main(int argc, char* argv[]) { using namespace boost; cmatch what; assert(regex_match("foo: bar", what, regex("([\\w]+):[\\s]*(.*)"))); assert(what.size() == 3); assert(what[1].matched); assert(what[2].matched); assert(std::string("foo") == std::string(what[1])); std::cout << std::string(what[2]) << "\n"; assert(std::string("bar") == std::string(what[2])); // fails return 0; } The last assert always fails, because regex::match insists on including the space after the ":" in the second match result, which seems wrong to me. I've tried giving various different combinations of flags to the regex ctor, although from what I can tell from the documentation the default flags should work. This is with VC7 and boost 1.30.2. For comparison, perl (5.6.1) does not seem to have this problem, as the following script illustrates: #!/usr/bin/perl print "matches: <$1> <$2>\n" if ('foo: bar' =~ /([\w]+):[\s]*(.*)/); Is there any way to get the behavior I want? Thanks, Scott McCaskill

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